The present invention relates firstly to a chimeric gene using the gene or CDNA (complementary DNA) of insulin driven by a promoter or fusion of promoters.
More specifically, it relates to the design of a chimeric gene formed by the fusion of the promoter of P-enolpyruvate carboxyquinase to the structural gene of human insulin, which allows the production of human insulin, physiologically regulated, in a tissue different from the pancreas.
The invention further relates to others objects which are described below.
Patients suffering from insulin dependent diabetes mellitus (IDDM) (type I) depend dramatically on the administration of the hormone. The interruption of the insulin administration results first in hyperglycemia and ketoacidosis, then coma and finally death if the hormone is not injected. Therefore, the life and the quality of life of these patients depend completely on the fluctuations of the insulin levels in their blood.
Gene therapy consists in the transfer of genetic material into cells of a patient with the purpose of treating an illness. At present, different approximations of gene therapy are being developed, based on the introduction of genes directly into animals or cells which are then transplanted.
However, the most important goal is not to be able to transplant successfully cells expressing the gene in an animal, but to make it possible for the gene to express in a regulated and physiologic way. The choice of a good promoter which drives the expression of the suitable gene is crucial in order to obtain suitable plasmatic levels of the corresponding protein.
In the case of diabetes, the question is to chose the promoter which drives the expression of the gene in order to obtain suitable insulin plasmatic levels for every condition of the individual. The overexpression of the insulin gene would result in hypoglucemia and a low expression of said gene would not modify the high glucose levels in the diabetic process.